JPS61257702A - Long canti lever cutting tool - Google Patents

Abstract

PURPOSE:To improve vibration-resistant effect by enlarging dynamic rigidity by performing heat treatment on a portion 0.35-0.45 times as much of a projec tion length from tool canti Lever point in a long canti Lever cutting tool such as a boring bar or a raw material cutting tool. CONSTITUTION:A high frequency coil 6 connected to a copper pipe 7 is set on a predetermined position of both faces of the shank 1 of a cutting tool provided with a cutting chip 2, and a heating center portion is heated to 600 deg.C-700 deg.C, and cooled with oil to retain tensile stress on the portion. When the position of the heat treatment portion 11 is made 0.4 times/in distance as much of a tool projecting length L from a tool canti Lever point 10 of a fixing means 3, the maximum effect is obtained in experiment where dynamic rigidity is maximum and total amplitude of trembling vibration is minimum. A flame method such as a gas burner can be used as a heat treatment method. Or rapid heating or rapid cooling of the entire shank 1 can be made by fitting a box to the heat treatment portion 11 of the shank 1.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a long cantilever cutting tool such as a boring bar or a material cutting tool.
In detail, a cutting tool with a long handle that protrudes outward from the gripping means of a cutting device is used. , it can be said that it is a tool with low rigidity because the protrusion length is large compared to the cross-sectional area. Therefore, when cutting is performed using these tools, chatter vibrations are likely to occur due to the tools themselves. As a result, machining efficiency and machining accuracy are reduced. Conventionally, several measures have been taken to alleviate the chatter vibration of the long cutting tool.

One of the countermeasures is seen in boring bars.Both sides of the boring bar are cut out so that the cross section is approximately rectangular.This gives directionality to the rigidity of the bar, and The cutting tip attached to the tip of the cutting tip is set at an optimal position in the rotational direction.

The second countermeasure, which is also seen in boring bars, is to increase the dynamic rigidity (static rigidity x damping coefficient ratio) by attaching damping means to the outer periphery of the bar. This includes methods using an impact damper and methods using a launch chest damper. The impact damper is a ring-shaped damper that is slidably attached around the handle of the bar to absorb vibrations of the bar itself during cutting. On the other hand, the lunch chest damper is a device in which a space formed within the bar is movably filled with blocks or viscous fluid, thereby absorbing vibrations of the bar itself.

The third measure, which can be found regardless of the type of cutting tool, is to manufacture the tool from a material with high static rigidity, that is, a material with a high Young's modulus, especially cemented carbide.

The fourth measure, which is applied to material cutting tools, is to increase the thickness of the handle.

Although four anti-vibration measures have been listed above, all of these conventional techniques have the following problems.

First, the first measure has very little anti-vibration effect.

In the second measure, the handle of the bowling bar becomes too large.

The third measure makes tools expensive.

In the fourth measure, the cutting width inevitably increases, resulting in poor yield, and if the thickness is made too large,
Cutting resistance increases, and as a result, chatter vibration may even increase.

Technical problem of the present invention Therefore, the technical problem to be solved by the present invention is to heat-treat the tool itself instead of conventional methods such as using special damping means or increasing static rigidity by changing the material of the tool. By applying this, the dynamic rigidity can be increased, thereby solving the various problems in the conventional example.

SUMMARY OF THE INVENTION In order to solve the above technical problems, the present invention was constructed as follows.

That is, when the protrusion length from the tool cantilever point is L, the structure is such that internal stress is left locally at a distance (k×L) from the tool cantilever point. However, in the above coefficient,
The value is between 0.35 and 0.45, with the most preferred value being about 0.
．． It is 40.

According to the above structure, the dynamic rigidity of the tool is dramatically increased, as is clear from the comparative experiment example described later, and the vibration resistance effect is also very excellent.

The reason why the vibration resistance of the tool is improved by the present invention is not yet clear, but the local residual stress and the stress that acts during cutting are combined and local plastic deformation occurs within the tool, resulting in a large hysteresis damping. It is speculated that this is to become

The above residual stress can be realized by heat treatment.

Generally, a method is employed in which the above-mentioned region is locally rapidly heated to a temperature above the tool tempering temperature and below the transformation point temperature A, and then rapidly cooled to cause tensile stress to remain in the above-mentioned region. If the rapid heating temperature is too high, the tool may be deformed or the tool may become unheated and softened, and conversely, if the rapid heating temperature is too low, sufficient internal stress may not remain. . Moreover, when the rapid heating temperature is A, the transformation point temperature or higher, the vibration resistance effect is small. The reason for this is not clear, but it may be because the rapid cooling of austenite generates needle-shaped crystals, which makes it difficult for slippage to occur at the interface between the heat-treated area and other areas adjacent to it. It is speculated that there is. The optimum heating temperature is the highest temperature below the A1 transformation point and at which the tool does not deform.

The rapid heat treatment mentioned above is generally performed by high frequency heating,
As another method, a flame method such as a gas burner can also be adopted. Alternatively, a mass may be attached to the heat-treated portion of the handle in advance, the entire handle may be rapidly heated, and then the mass may be rapidly cooled. In this case, since the cooling rate of the heat-treated part to which the mass is attached is slow, a difference in cooling rate occurs between the heat-treated part and other parts, and as a result, tensile stress remains in the heat-treated part.

Example An embodiment of the invention is shown in FIG. 1.2.

The illustrated embodiment relates to a material cutting tool. In the figure, 1 is a thin plate-shaped and long handle, 2 is a cutting tip attached to the tip of the handle 1, and 3 is a fixing means for cantilevering the handle l of this cutting tool.

As shown in FIG. 2, the cutting tool has an elliptical heat treatment part 11 at a predetermined position on its handle l. This heat treatment section 11
The implementation locations are as follows. That is, when the tool protrusion length from the tool cantilever point 10 of the fixing means 3 is L, and the distance from the tool cantilever point of the heat treatment section 11 is σ, e is expressed by the following equation.

Q#0.40×L0 Comparative Experimental Example The effects of the present invention will become clearer from the following comparative experimental example conducted by the inventors.

The present inventors performed heat treatment on several parts of the protruding length of the handle 1 of the material cutting tool shown in FIG. 1.2, and also tried actually cutting a material using this tool.

(Test tool) As mentioned above, the test tool is the material cutting tool shown in Figure 1.2, its material is Tool 11isK5 (JIS standard), and its specifications are as shown below. be.

・Tool total length A: 400y ・Width B of handle 1: 80 mm ・Thickness G of handle 1: 3 mrtt ・Width CXD of heat treatment section 11: 45X15xx The heat treatment of the heat treatment section 11 was performed by the following method. That is, as shown in FIG. 3, the high frequency coil 6 (width E 550°C) or higher to 6006°C to 700°C, and then cooled in oil. The heat treatment position is 34 u+ (fl = 116 mm), 75 mm C from the tip of the cutting tip.
Q = 75mm), 92xm ((= 58mm), 150
xx((1=O).

Note that the hardening temperature of the tool is 825°C. In addition, a carbide tip was used as the cutting tip.

Test material Test material 5 is carbon steel 545CCJIS standard) (No. 4
figure). The width dimension P×0 of the cut surface of this sample material 5 is 50×4
It is 0M11.

Experimental Method The machine used in the experiment was a side boring machine, and the experiment was conducted in the manner shown in Figure 4. That is, the handle 1 of the material cutting tool is fixed to the face plate 3a of the machine (the protruding length L of the tool is 1).
The sample material 5 placed on the table 12 was cut into slices by rotating at a rotation radius H (=450 mm).

Due to mechanical structure constraints, we decided to send the tool downwards.

The cutting conditions were: cutting speed: 100.4 m/m1n (35
, 5 rpm), feed rate 0, 11111/rev, dry cutting. The chatter vibration of the material cutting tool was measured by a non-contact displacement meter 4 fixed at a distance N (=20 im) above the sample material 5.

Experimental Results The results shown in FIGS. 5(I) to (V) were obtained by the above experimental method. In each figure, the horizontal axis shows time and the vertical axis shows the amplitude of chatter vibration.

FIG. 5(1) shows the results without heat treatment.

Figure 5 (II) shows (1=116+x0.77×L
) is shown. Figure 5 (DI) C, (1=75J
The case of fm (=0.50×L) is shown. FIG. 5 (■) shows the case where ρ=581tII and 0.40xt.

FIG. 5(V) shows the case where Q=0. As is clear from comparing each figure, the chatter vibration is the least in the case of FIG. 5 (IV).

In the above experimental results, as a result of considering the case where the heat treatment position was e=58 mm, an interesting Jv fact was discovered. Figure 6 shows the vibration 8 of the first mode of the cutting tool and the vibration 9 of the second mode, where e is approximately 0.40×
It was found that this part corresponds exactly to the antinode of the bending vibration of the second-order mode 9. From this, it is not possible to immediately determine the optimal position of the heat-treated part to be the position of the antinode of the bending vibration of the secondary mode, but it is possible that other higher-order modes such as secondary, tertiary, etc. are involved. However, in general, the optimum position for this heat treatment can be said to be the position of the antinode of the secondary mode.

The reason why the heat-treated material cutting tool has excellent vibration resistance is that the heat treatment improves the dynamic characteristics of the tool. Therefore, the present inventors developed the impulse hammer method (impulse hammer device gives a blow to the tool, a vibration meter attached to the tool detects the vibration of the tool, and a dynamic stiffness measuring device is used to measure the amplitude and damping of each bending vibration mode. The dynamic characteristics of the cutting tool were measured using the method of determining the coefficient ratio, and the relationship with the chatter amplitude was investigated. The vibration was applied in the same direction and position as the cutting resistance, and the response point was also 40 mm from the cutting edge. In addition, the static properties of the cutting tool in the thickness direction were also measured at the same time. The results are shown in FIG. In FIG. 7, the horizontal axis shows the heat treatment position from the tip of the tool, and the vertical axis shows the values of each characteristic. As shown in the figure, the heat treatment position is 92xtBD beyond the tool tip (2 = 58m
In the vicinity of m (0.40 It is clearly seen that

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1.2 is a plan view and a front view of the material cutting tool, and FIG. 3 is a front view of the main part showing a state in which high-frequency heating is applied to a predetermined position of the handle of the material cutting tool. Figure 4 is a schematic diagram showing the experimental method, Figure 5 (I)
~(V) is a graph showing the results obtained by the experimental method shown in FIG. 4, FIG. 6 is an explanatory diagram showing the relationship between the constituent modes and secondary modes of bending vibration of the cutting tool and the heat treatment position,
FIG. 7 is a graph showing the relationship between the heat treatment position, static property, dynamic stiffness, etc. l...handle, 2...cutting blade tip, 3...fixing means,
4... Non-contact displacement meter, 5... Work material, 6... High frequency coil, 7... Copper pipe, 8... Vibration in the -th mode, 9... Vibration in the second mode , lO... tool cantilever point, 11... heat treatment section, 12... table. Patent applicant: Agent of Kobe Steel, Ltd.
Two patent attorneys: Aohaku Ao Haga Figure 1 Figure 2 Figure 5 (Eng) Figure 5 (m) Figure 5 (IV) Figure 5 M Ginma Figure 6

Claims (1)

[Claims] 1. When the protrusion length from the tool cantilever point (10) is L,
A long cantilevered cutting steel tool characterized by locally retaining internal stress at a distance (k×L) from a tool cantilever point (10). However, the above coefficient has a value of 0.35 to 0.45. 2. The first method characterized in that the above-mentioned region is locally rapidly heated to a temperature higher than the tool tempering temperature and lower than the A_3 transformation point temperature, and then rapidly cooled to cause tensile stress to remain in the above-mentioned region.
The long cantilever cutting tool described in section.